1 BT headset-2 phones

Of course, most of the higher end BTs can use multiple devices at one time, some car kits can have up to 8+ at one time. Best bet for those would either be a BlueAnt z9i or a Jawbone 2. I've had both for a while and they are great!

The BlueParrot Xpressway has the ability to link to two different headsets simultaneously and pickup calls on either unit when it rings. It also has 3 different wearing styles (neckband, headband, earhook). You can find them at most of the major trucking stops (Flying J, TA Trucking, Pilot, Love's)